Ok, let's just get one thing out the way first. The plot and the dialogue for this gobsmacking leviathan of a movie have clearly been scrawled on the back of a beer mat over a lunchtime pint or, in James Cameron’s case, more likely on the back of a White Star Line napkin while downing a pint of organic wheatgrass juice (apparently it helped with his ‘high energy, must-stay-awake’ antics when creating that other blue-tinged world in Titanic).

The levels of energy required to stay awake on the set of that film or his new epic opus must have been monumental. The CGI team had to work for 57 hours on each frame of film, and at 2 hours and 40 minutes that’s a lot of frames to render. Those lads must now be desperate to hang out with the directors of very short films.

So to reiterate, Avatar’s plot and dialogue are definitely wanting and the film’s a stretch too long by around twenty minutes or more (well, it is a Cameron flick).

But apart from that and on a purely visionary, visceral and adrenaline fuelled level and having seen it on a giant Imax screen courtesy of the Glasgow Science Centre in the format for which it was designed, it is a truly jaw dropping and astonishing experience. Sitting next to me was a friend who, as an experienced film-maker himself (and knowing how hard he is to please) leaned over about twenty seconds into the film and whispered ‘that’s amazing!’

I had to agree. In fact for the first ten minutes of the film I was so overwhelmed by the scale and startling reality of the 3D experience that I was unable to follow the story or listen to the dialogue as my brain was still trying to compute what I was seeing. It wasn’t until I forced myself to concentrate on following it rather than gawping open mouthed that I felt like I entered into the film.

The new 3D technology Cameron’s created which gives a more realistic sensation of depth perception (three focal planes from close, mid and distant horizon) are clearly the beginning of a revolution in the way films will be made from now. If Hollywood’s been panicking over the download generations hold on cinema attendances I think part of the solution has been found (although making some decent films and improving multiplexes might help). How Avatar will play out in regular cinemas I can't say. I’m sure the experience will be somewhat diminished from the IMAX sensation, but the new 3D effect should still be convincing.

Set in 2054, the plot is a hybrid of Cameron’s own Aliens in terms of the way the military is depicted and the hardware it uses and a liberal helping of Dances with Wolves in terms of the lone hero’s journey into an alternate society. There’s also elements of The Force from the Star Wars saga which here has been morphed into an alien world’s version of our own Gaia theory.

That world is Pandora (hmm – I wonder what happens if you open up that particular box?) and its rich not only in a vital fossil fuel known as Unobtanium (geddit), but also in exotic flora and fauna and a humanoid-like indigenous species the Navi. The Navi at twice the height of humans, blue skinned, ridiculously well-toned and are a cross between Edinburgh’s own pagan Beltane warriors and Native Americans, dressed like a Nubian tribe.

Unfortunately for Random Non Specific Giant Corporation, the valuable and rare Unobtanium is precisely where the Navi settlement is located and is surrounded by their traditional sacred sites. A team of scientists and biologists are sent in to negotiate a resettlement deal with the army on standby if the Unobtanium proves…well, unobtainable.

The method of initially engaging diplomatically with the Navi is by transplanting the human consciousness into Navi-humanoid hybrid clones, hence the term avatar. Ex marine Jake Sully (Sam Worthington of Terminator Salvation) who’s lost his legs in combat is sent in to observe the settlement, blend in and report back to base, providing the military with strategic Intel on the layout of their compound. Naturally he gets a kick out of the experience of being able to walk and run again while his real mind is in a state of suspended animation.

It's not rocket science to predict what happens next. Sully’s avatar has trouble blending in at first but gradually learns the ropes. He begins to love their way of life, falls in love with his female tutor (a scantily clad shapely Navi designed to appeal to the teenage boy demographic – undoubtedly the target audience) and then ultimately stays behind to help them defend their homeland when Pandora’s Box bursts open.

There is a nice touch in that the Navi have their own version of the avatar experience by communing with the planet around them, connecting their consciousness to it through their own set of organic fibre optical hair extensions. It sounds silly but its strangely convincing.

That’s all you need to know. There’s nothing really more to it than that. It's all daft seen-it-before nonsense, but where Avatar is brilliant is in the details and how it’s presented in the new format.

Cameron’s come up with some nice gimmicks and elegant visuals to show off his new set of tools. An early moment that struck me was a giant spacecraft gliding towards us gradually revealing the planet Pandora and its orbiting moon but only as a reflection in the craft’s solar panels. It’s a brilliant conceit – the spacecraft is already in 3D but so is the reflection appearing on its surface. It’s the many little touches like this that added up to a unique experience.

There’s also some magnificent design and detail in the lush Navi forest at night where all the plants and vegetation glow with bio luminescence and multi coloured iridescent light. Your eye scans the whole frame taking in details off in the distance or a fern leaf that seems to nearly brush past your cheek. At one point I got distracted and irritated by a few flies buzzing around in the theatre in front of the screen. It was only when the shot changed that I realised they were part of the film – that’s how convincingly real some of the shots are.

The 3D seems to work best when the action and movement is minimal or when the shot is locked off allowing you to really study it at your leisure. It also seemed to work best in the mid ranges of the film’s (or perhaps my own eyes’) focal plane, where the action or focus was from a few feet to twenty or thirty feet beyond: so corridors, rooms, the forest floor, inside a spacecraft seemed much more real to me than distant landscapes or close ups of the Navi, although extreme close ups of human’s eyes, faces and skin looked like it was right in front of you. Naturally, the real thing always looks more, well real.

Where it was less convincing was in the vast distant landscapes and floating islands that hover above Pandora’s surface. They looked pretty, but felt almost two-dimensional at times. Additionally when the frame was jam-packed with action, particularly during some of the fast-paced and intense battle scenes. When you have hundreds of elements flying around like a hyperactive Jackson Pollock painting I found that the experience flattened out. Perhaps, there’s only so much the human eye or brain can take in at once.

There are a handful of great set pieces including Sully’s first encounter with Pandora’s own set of dinosaurs, his learning to handle and fly the pterodactyl like creatures that live high above the forest and a scene involving a swarm of firefly-esque jellyfish. The hair did go up on the back of my neck a couple of times and I involuntarily lurched forward in my seat when the camera tipped over a cliff during a chase sequence. And that’s what we’re paying our money for, to be stunned momentarily by the design and to be fooled even just for a few seconds here and there by something approximating reality, even if it’s on a fictional planet.

So no revolution in storytelling but in terms of design and the 3D experience Avatar is quite remarkable.